Re: cataloguing NOT NULL constraints

On 2023-Sep-05, Peter Eisentraut wrote:

> The following information schema views are affected by the not-null
> constraint catalog entries:
>
> 1. CHECK_CONSTRAINTS
> 2. CONSTRAINT_COLUMN_USAGE
> 3. DOMAIN_CONSTRAINTS
> 4. TABLE_CONSTRAINTS
>
> Note that 1 and 3 also contain domain constraints. So as long as the domain
> not-null constraints are not similarly catalogued, we can't delete the
> separate not-null union branch. (3 never had one, so arguably a bit buggy.)
>
> I think we can fix up 4 by just deleting the not-null union branch.
>
> For 2, the simple fix is also easy, but there are some other options, as you
> discuss above.
>
> How do you want to proceed?

I posted as a patch in a separate thread[1]. Let me fix up the
definitions for views 1 and 3 for domains per your comments, and I'll
post in that thread again.

[1] https://postgr.es/m/202309041710.psytrxlsiqex@alvherre.pgsql

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